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ground, and how exactly the amount of the 
surplus of produce (in value) over expenses 
is settled. There obviously cannot be a sur 
plus on the marginal land, when any other 
available land remains uncultivated, if we 
include in the labour the work done in the 
way of direction by the farmer himself, 
because it is assumed that what is received 
for the produce when no rent is paid will be 
just sufficient adequately to remunerate the 
whole of the factors engaged in working 
the land. The surplus derived from the 
other lands will evidently be the outcome of 
their differential advantages, and this surplus 
consequently will be the rent. 
In an attempt to settle these further points 
there is nothing to baffle those who have 
acquired deftness with the marginal method. 
Let us think of labour and capital as made 
up of doses of productive agents each of a 
given value. Thus let us mean by a dose of 
labour and capital 20s. spent to the best-known 
purpose on labour (including the farmer’s 
work), machinery, seed and other farming 
necessities in the working of the land. One 
dose, of course, might stand for much labour 
and little instrumental capital, while another 
dose might stand for little labour and much of 
the other things required in agriculture. Now